Marine Gen. John R. Allen wants 1,700 more military personnel to lead hundreds of new advisor teams to be assigned beginning next year to Afghan units battling the Taliban insurgency, officials say.

Reporting from Washington — The U.S. commander in Afghanistan has prepared a request for more troops to serve as advisors for Afghan military units, a sign that Washington and its allies are trying to speed up the hand-over of combat operations to the Afghans as they prepare to withdraw, U.S. and NATO officials said.

The stronger emphasis on training may keep more U.S. troops on bases next year and help reduce U.S. military casualties before presidential elections next November. President Obama's Afghan policy is already an issue.

Marine Gen. John R. Allen, who took command in Afghanistan last summer, wants 1,700 more military personnel — mid-level officers and senior enlisted troops leading hundreds of new advisor teams to be assigned beginning next year to Afghan units battling the Taliban insurgency, the officials said.

It will take time to identify the right mix of troops, and Allen's request has yet to be submitted to the Pentagon. The move is part of a major retooling of Afghanistan strategy under discussion by Obama and his national security team, aimed at ensuring Afghan forces are ready to take on the militants by 2014, when the last U.S. combat units are scheduled to pull out.

Allen and other senior U.S. military officers generally support the idea of pushing the Afghan army into the lead sooner. Aides say it makes sense to test how well it performs while large numbers of U.S. troops still can come to Afghan soldiers' assistance if necessary.

Moreover, support for keeping combat troops in Afghanistan for three more years has withered in other North Atlantic Treaty Organization countries. This has added impetus to the White House drive to speed up the transition to Afghan forces.

In some ways, Obama is attempting to follow the model he set in Iraq, when he changed the U.S. military mission to emphasize training of Iraqi forces. In August 2010, he announced that the Iraqi military had lead responsibility for the nation's security. U.S. casualties in Iraq have plummeted, and the last U.S. combat troops are scheduled to be withdrawn next month.

"Our top priority right now is building" the Afghan army and police, said a senior U.S. general involved in the discussion. But "it's a perilous path we're on right now.... The Afghans can't carry the load by themselves."

Obama has ordered the withdrawal of 30,000 U.S. troops by September. That will leave about 68,000 U.S. troops in Afghanistan.

Defense Secretary Leon E. Panetta hinted at the Obama administration's new thinking during a news conference last week with the Canadian defense minister in Halifax, Canada.

"We're trying to get the Afghan army, the Afghan police, to assume more of the responsibilities with regards to combat operations," he said. "That's going to depend a lot on Gen. Allen and working with ISAF to determine how best to make the transition from a combat role to an advise-and-assist role," he said, referring to NATO's International Security Assistance Force.

Administration officials said the White House planned to formalize the shift to a more advisory role at a NATO summit that Obama is playing host to in May in Chicago.

At last year's NATO summit in Lisbon, Obama and other NATO leaders agreed to begin handing control of areas with low insurgent activity to Afghan military units. Afghan troops have since assumed control in some parts of the country, and U.S. forces plan to turn over more areas next month.

But the NATO plan called for waiting until 2014 to give Afghan forces responsibility for all combat operations. White House aides and other governments with troops in Afghanistan are now increasingly worried about that timetable.

By waiting so long to give Afghan troops the lead in areas where the insurgency is strongest, the plan magnified doubts about whether Afghan soldiers could assume the combat burden once U.S. forces finally left.

"We want [Afghan forces] to be in the lead. It's part of the current plan and the whole intent is to morph over time," a senior NATO officer in Afghanistan said. "But we have to figure out what trainers and advisors will be required. They're doing the math now."

U.S. military officials have cautioned the White House not to expect too much of the Afghan units, many of which are beset with operational and personnel problems.

Even with hundreds of additional U.S. advisor teams, American infantry and special operations units will need to lead some of the fighting for the next three years, especially in eastern Afghanistan, where the insurgency remains strongest, the officers said.

Fighting in Afghanistan typically tapers off in winter, when conditions can make it difficult for insurgents as well as regular military units to move. If the transition to a role that emphasizes advising and training starts late next year, that would be after the U.S. and its allies have had another full season to try to further weaken the insurgents.